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Shimla, India

Himachal Pradesh University is a public non-profit university located in Shimla nearly 5 km away from the town of Summer Hill, in the vicinity of the Indian Institute of Advanced Study. It is wholly financed by the Government of Himachal Pradesh and the University Grants Commission, New Delhi. Wikipedia.

Kumar A.,Himachal Pradesh University | Ahluwalia P.K.,Himachal Pradesh University
Journal of Alloys and Compounds | Year: 2013

We have performed first principle pseudopotential and numerical pseudoatomic orbitals basis set based calculations to study the influence of slab thickness on the electronic and dielectric properties of niobium dichalcogenides (S, Se, Te). We have taken bulk, mono, bi, quadri and six-layer setup for this study. The importance of semicore states in Nb pseudopotential has been investigated. Electronic band structures of studied materials show splitting of the bands of the order of 0.7 eV at Γ point due to interlayer interactions for all the materials under consideration. Electron energy loss spectra (EELS) for in-plane polarization shows 0.65 eV (6.5 eV), 0.75 eV (7.5 eV) and 0.55 eV (6.9 eV) red shift in energy of π(π + σ) plasmons peaks respectively for NbS2, NbSe2 and NbTe2 by reducing the slab thickness from bulk to monolayer, while for out-of-plane polarization, approximately ≈6.3 eV red shift in π + σ plasmons peak has been found for all the studied materials on reducing the number of layers from bulk to monolayer. Interband transitions energies are found to remain same irrespective of the quantum confinement effect for all the dichalcogenides of Nb with an additional interband transition at 3.2 eV for NbTe2. © 2012 Elsevier B.V. All rights reserved.

Thakur V.K.,Washington State University | Thakur M.K.,Himachal Pradesh University
Journal of Cleaner Production | Year: 2014

Natural polysaccharide based hydrogels display unique properties such as biodegradability, biocompatibility, stimuli-responsive characteristics and biological functions making them a materials of choice for diverse applications. Indeed during the last few years, a number of biorenewable polymers based hydrogels have attracted great interest for miscellaneous applications including biomedical, toxic ion removal and water purification. Keeping in mind the advantages of biorenewable polymers, this article summarizes for the first time, the recent development in psyllium polysaccharide based hydrogels. Different methods for preparation of polysaccharide hydrogels along with characterization, their swelling behavior and different mechanisms of solvent diffusion are critically reviewed. This article also comprehensively discusses the structure-property relationships of polysaccharide hydrogels and highlights the application potential for prime performance of the resulting hydrogels. Effect of different reaction conditions and monomers on different properties of the resulting hydrogels have been explored. The most important properties of polysaccharide hydrogels relevant to their biomedical/environmental applications are also identified, especially for the use of polysaccharide hydrogels as drug delivery/flocculant and superabsorbent systems. It is anticipated that the interest in natural polysaccharide based hydrogel will continue to grow as value - added green materials for multifunctional applications.

Kumar A.,Himachal Pradesh University | Kanwar S.S.,Himachal Pradesh University
Bioresource Technology | Year: 2011

In the present work we have evaluated synthesis of ethyl ferulate by the esterification reaction of ferulic acid and ethanol catalyzed by a commercial lipase (Steapsin) immobilized onto celite-545 in a short period of 6h in DMSO. The immobilized lipase was treated with cross-linking agent glutaraldehyde (1%; v/v). The optimum synthesis of ethyl ferulate was recorded at 45°C, pH8.5 and 1:1 ratio of ethanol and ferulic acid. Co2+, Ba2+and Pb2+ ions enhanced the synthesis of ethyl ferulate Hg2+, Cd3+and NH4+ ions had mild inhibitory effect. The celite-bound lipase produced 68mM of ethyl ferulate under optimized reaction conditions. © 2010 Elsevier Ltd.

Kumari S.,Himachal Pradesh University | Chauhan G.S.,Himachal Pradesh University
ACS Applied Materials and Interfaces | Year: 2014

Mercury is a highly toxic environmental pollutant; thus, there is an urgent need to develop new materials for its simultaneous detection and removal from water. In the present study, new oxidized cellulose-based materials, including their Schiff bases, were synthesized and investigated as a sensor-adsorbent for simple, rapid, highly selective, and simultaneous detection and removal of mercury [Hg(II)] ions. Cellulose was extracted from the pine needles, etherified, oxidized, and modified to Schiff base by reaction with l-lysine. The well-characterized cellulose Schiff base materials were used as a sensor-adsorbent for Hg(II) from aqueous solution. Hg(II) sensing was analysed with naked-eye detection and fluorescence spectroscopy. Schiff base having a decyl chain, C10-O-cell-HC=N-Lys, was observed to be an efficient adsorbent with a very high maximum adsorption capacity of 258.75 mg g -1. The data were analyzed on the basis of various kinetic and isotherm models, and pseudo-second-order kinetics and Langmuir isotherm were followed for Hg(II) adsorption. © 2014 American Chemical Society.

Thakur V.K.,Washington State University | Thakur M.K.,Himachal Pradesh University | Gupta R.K.,Indian Institute of Technology Kanpur
Carbohydrate Polymers | Year: 2014

In the present study, free radical induced graft-copolymerization of natural cellulosic polymers (Grewia optiva) has been carried out to develop the novel materials meant for green composites and many other applications. During the graft copolymer synthesis diverse reaction parameters that significantly affect the percentage of grafting were optimized. The structural, thermal and physico-chemical changes in the natural cellulosic polymers based graft copolymers have been ascertained with scanning electron micrography, Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and swelling studies. The swelling studies of the grafted cellulosic polymers have been carried out in different solvents to assess the possible applicability of these natural polymers. Green composites were also prepared using raw/grafted cellulosic polymers. It has been found that grafted polymers (Grewia optiva) based green composites gives better tensile properties than the parent natural cellulosic polymers based composites. © 2014 Elsevier Ltd.

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